Sister-in-law of the Heroine in a Childcare Novel

Sister-in-law of the Heroine in a Childcare Novel summary:

I was reincarnated as a minor villainess in a fluffy, family-healing novel. Specifically, as a pathetic imperial princess destined to become obsessed with the adorable female lead’s eldest brother, only to end up poisoning the female lead and meeting a miserable demise.‘Fine! I’m dumping all of you first!’ With that vow, I was all set to pack up and flee. But after accidentally saving the female lead, things went completely off the rails.“Anyone who dares to touch my sister? I will hunt them to the ends of the earth and tear them to shreds.” “The Imperial Family? An incompetent institution that only brings Titania unhappiness. Why should I care what happens to it?” “Hahaha! Those fools call me a mad dog, so why are their heads so empty? If a mad dog chooses who it bites, is it even a mad dog anymore?”P-Please, calm down, everyone! I’m just trying to run away to a beautiful seaside villa with crashing waves to enjoy my dreams, my hopes, and my heaps of money! I wish you all the best!…At least, that’s what I thought.“…When I thought… you were truly dead, I……”His golden eyes locked onto mine, swirling with emotions I couldn't begin to read. Just looking into them made me feel like I was drowning.“…It felt like I was trapped in an endless nightmare, Tia.”He whispered desperately, pleading with me never to vanish from his sight again. Yet, the way he gripped my hand—binding me to him so I could never escape—left me utterly speechless.To make matters worse…“It’s okay if you hate my big brother! It’s okay if you find my dad annoying! Just please, don’t hate our Duchy’s money!”The cute-as-a-button female lead suddenly shoved the keys to the underground vault containing all the Duchy’s treasures into my hands.“Is everything just too much hassle? Then pick me instead of my brother. You don’t have to bother being a Duchess. I'll stay by your side anytime, anywhere. What? Stop talking like a dog? Woof, woof! Arf, grrr, bark!”Even the female lead’s second older brother, who used to look at me like an absolute eyesore, has lost his mind. What is wrong with you people?! +